Electric field gradient distributions about strontium nuclei in cubic and octahedrally symmetric crystal systems

Strontium nuclei (Sr87) in natural abundance are examined with magic angle spinning (MAS) nuclear magnetic resonance (NMR) of powder samples possessing either simple cubic (SrO) or fluorite-analogue (SrCl2 and SrF2) structures. The MAS spectra of these samples reveal a sideband pattern resulting from first order quadrupolar broadening of the outer transitions brought about by imperfections in the crystal structure. These imperfections lead to a distribution of electric field gradients (efgs) that can be characterized in these cases by fitting integrated sideband intensities as a function of spectral frequency with a Lorentzian function. Strontium oxide is simple cubic and found to have an isotropic Sr87 chemical shift of 340±1ppm with respect to 1 M SrCl2 (aqueous) and an efg distribution with a full width at half-height (FWHH) of 50.4±2.5kHz. Strontium chloride (anhydrous) is isostructural with fluorite and was found to have a Sr87 chemical shift of 45.9±1.2ppm and an efg distribution with a FWHH of 30.9±1.4kHz. Strontium fluoride is also isostructural with fluorite and had a Sr87 chemical shift of -13.0±1.2ppm and an efg FWHH of 104±18kHz.